Originally Posted by bigblock427
Afaik there are 3 systems for spacers available
Spacers without centric ring - which i never would recommend - but
afaik there are no 5 mm, or 10 mm spacers with centric ring on the market - o.k. german market

Wrong! Here is a link to 10MM hub centric spacers with rings for $60 per pair. I have these, and can attest to the very high quality of them. I have 10MM in the front, and 15MM in the back.
Steel Hub Centric Wheel Spacers Mercedes 10mm
They also sell 5MM hub centric flat spacers.
http://www.ezaccessory.com/Billet_Hu...p/sp55112m.htm
All made in Germany